Recombinant proteins are used to treat a number of human disorders including diabetes, neutropenia, anemia, and chronic musculoskeletal disorders of the elderly. Muscle and bone wasting associated with aging can be attenuated using proteins such as growth hormone (GH), and insulin- like growth factors, but their delivery by daily injection is not optimal since the proteins degrade rapidly in vivo. Cell-based delivery of proteins from genetically-modified implanted cells may provide a more effective and cost-saving alternative. The long-term objective of this project is to develop an effective, economic, and reversible cell-based delivery system for proteins based on a new form of ex vivo skeletal myofiber gene therapy. Cell Kinetics, Inc. holds the exclusive licensing rights to technology whereby genetically modified myoblasts are tissue engineered into organ-like skeletal muscles (organoids) which can be reversibly implanted for the long-term systemic delivery of proteins (Muscle Organoid Delivery System - MODS TM). MODS TM secreting recombinant human GH (rhGH) attenuate muscle disuse atrophy in a murine hindlimb unloading model and the specific aim of this project is to directly compare the effectiveness of MODS TM secreting rhGH to rhGH injections in attenuating muscle atrophy. These studies will help establish the effectiveness of treating chronic muscle wasting disorders with a cell-based delivery system. PROPOSED COMMERCIAL APPLICATION: Cell kinetics, Inc. will develop a new form of muscle gene therapy for cell-based delivery of proteins to treat numerous chronic human musculoskeletal disorders such as muscle and bone wasting in the elderly. There is a large market for the development of such delivery systems since the clinical need is large ($149 billion in health care costs in 1992), manufacturing high purity recombinant proteins for injection is expensive, and injections are not the optimal delivery method. Long-term cell-based delivery of these factors will result in considerable convenience to the patient and savings to the health care system.